I've just cleared about 40 feet x 20 feet of 4-foot-high brambly stuff and
bindweed from the far end of Mum's garden, either cutting off at ground
level or pulling them out.

I was going to spray the whole area with weedkiller to stop them coming back
but all the ones I looked at in B&Q said to spray onto the leafy parts (I
bought the Weedol Rootkill Plus in the end). So do I have to wait until they
start reappearing before treating?

Also, I've got a huge pile of the stuff I cut off, will it eventually dry
enough to be put in a bonfire without generating huge amounts of smoke?